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Multiplexed current input to ADE7880

Hi,

Is it possible to connect more than 3 current inputs to ADE7880 via multiplexing.

For eg; we are collecting 16 inputs from CT.'s and multiplexed those inputs and sending to adc pins of microprocessor.

Like that is it possible to connect this multiplexed input to channel A,B,C of ADE7880?

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  • Anything is possible but at a cost. 

    When switching multiple ct's to a single adc input you have to wait for the data to settle. The sinc , lpf high-pass and lpf2 filters need to settle and this can take seconds in total time before the output meets datasheet specs. 

    You will also need to calibrate each CT and change any gain/phase correction for each CT. 

    I think This is an over complicated task. 

    Why would you not use multiple ade7880. This seem to be a better option. 

    Dave 

  • Hi,

    If I use five ADE chip, it will have five  SPI out from ADE to processor. So how can we connect this five ADE chip to a single processor.

    What is the difference between ADE9000 and ADE7880?

    For ADE9000, i have doubt of can we connect Rogowski & CT to the same circuit (or  doing in software) , for ADE7880 we have two different circuits for Rogowski & CT

    if we go for multiple Ade chips, we need to have 5 Ade chips to connect 15 lines (R, Y, B Phase) that is 5 equipment's & 5 Neutral lines. For power signature analysis, which one is better ADE9000 or ADE7880? What is the major difference between these two ADE chip.

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  • Hi,

    If I use five ADE chip, it will have five  SPI out from ADE to processor. So how can we connect this five ADE chip to a single processor.

    What is the difference between ADE9000 and ADE7880?

    For ADE9000, i have doubt of can we connect Rogowski & CT to the same circuit (or  doing in software) , for ADE7880 we have two different circuits for Rogowski & CT

    if we go for multiple Ade chips, we need to have 5 Ade chips to connect 15 lines (R, Y, B Phase) that is 5 equipment's & 5 Neutral lines. For power signature analysis, which one is better ADE9000 or ADE7880? What is the major difference between these two ADE chip.

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  • ADE9000 and ADE7880 will have the same setting issue if you multiplex sensor to the adc input. 

    I think the question is can you get all the adc samples out fast enough. 

    The ade9000 has a waveform buffer  so getting the data out might be easier. The spi can run at 20Mhz. 

    you can also get 32Ksps data from the sample buffer. The ADE9000 has better snr. The ade9000 does not have the harmonic engine. 

    I think you will find the ADE9000 more useful for signature analysis using the waveform buffer. This will require the micro to calculate the fft.

    Dave

     

  • Hi,

    If I use five ADE9000 Chip to connect 15 lines(R,Y,B phase),it will have 5 SPI out, So how can we connect this five SPI out to a single processor?  

  • You can use a single spi port with multiple chip selects. The spi speed can run at 20Mhz. Is this fast enough for your application? If not you can split your 5 parts between 2 spi port2. 3 chip selects on spi port 1 and 2 on spi port 2. How you divide the parts  and how many ports will depend on how fast you need your data. 

    Dave

  • So then do we need to use five each ADUM4151BRIZ and ADUM6404ARIZ for each five ADE9000 chip?

    For ADE9000, i have doubt of can we connect Rogowski & CT to the same circuit by removing burden resistors

    Also in delta connection, there is no neutral line.

  • Yes would would need isolation if you expect the ground domains between each ADE9000 to be different. If they are the same domain then you could isolate after the micro.  The ADE9000 has the same settling issues when you mux sensors. When switching from ct to Rogowski there will be more settling from the integrator. If you do mux the burden and any non common anti-alias should be on the input of the mux. The standard anti-alias on the output of the mux.